1. Field of the Invention
The present invention is directed to an agglomerated fibrous ion exchange cellulose composite which will effectively adsorb and immobilize enzymes.
More particularly, the present invention is directed to an agglomerated fibrous ion exchange cellulose composite containing glucose isomerase which exhibits improved porosity characteristics.
2. Description of the Prior Art
Early processes for preparing fructose containing solutions whereby glucose was converted to fructose in the presence of alkaline catalysts or sucrose was inverted to glucose and fructose by means of acid have been largely superseded by enzymatic methods. The present commercial methods involve the isomerization of glucose to fructose by glucose isomerase elaborated by various genera of microorganisms.
Because of the economics involved in producing glucose isomerase, it is of the utmost importance to use the isomerase under conditions whereby maximum yields of fructose are produced using minimum quantities of glucose isomerase. Moreover, the conditions for isomerization should be such that minimal quantities of objectionable by-products are produced.
In recent years, more economical methods for producing fructose containing solutions have been developed utilizing glucose isomerase bound or immobilized on inert support materials. Such materials include various polymeric substances such as derivatized cellulose, ion exchange resins and synthetic fibers, glass, insoluble organic and inorganic compounds, etc. Glucose isomerase has also been encapsulated or englobed in suitable materials but such preparations suffer from the disadvantage that they generally cannot be reused.
Cellulose occurs in nature as a linear polymer comprised of anhydroglucose units joined together by .beta.-1,4 glucosidic bonds. Each anhydroglucose unit contains three free hydroxyl groups capable of reacting with appropriate reagents to form insoluble cellulose derivatives which, due to their relative inertness, large surface area and open, porous structure, have a high adsorptive or ion-exchange capacity for protein molecules.
The preparation and utilization of ion exchange enzyme adsorbents derived from cellulose are known in the art. Peterson and Sober, J.A.C.S., 78, 751 (1956) and Guthrie and Bullock, I/EC, 52, 935 (1960) described methods for preparing adsorptive cellulose products which could be utilized to separate or purify enzymes and other proteins. Tsumura et al., Nippon Shokuhin Kogyo Gakkaishi, 14, (12), (1967) disclosed binding glucose isomerase to DEAE Sephadex.
U.S. Pat. No. 3,708,397 to Sipos relates to a process for immobilizing glucose isomerase on basic anion exchange celluloses. U.S. Pat. No. 3,823,133 to Hurst et al. is directed to a method for preparing cationic cellulose ethers having a high adsorptive capacity for enzyme and other proteinaceous materials. U.S. Pat. No. 3,838,007 to van Velzen sets forth a process in which an enzyme preparation is obtained in particulate form. U.S. Pat. Nos. 3,788,945 and 3,909,354, both to Thompson et al., disclose continuous processes for converting glucose to fructose by passing a glucose-containing solution through fixed or fluidized beds containing glucose isomerase bound to various cellulose products. U.S. Pat. No. 3,947,325 to Dinelli et al. is directed to the preparation of cellulose containing englobed enzymatic material. The cellulose is formed from an emulsion comprising an aqueous enzyme solution and nitrocellulose. U.S. Pat. No. 3,956,065 to Idaszak et al. is concerned with a continuous process for converting glucose to fructose whereby a glucose containing solution is passed through a bed comprising a cellulose derivative having glucose isomerase immobilized thereon and non-porous or granular polystyrene beads. The beads inhibit packing and channeling of the bed when such is used in flow reactors. Peska et al. in an article entitled "Ion Exchange Derivatives of Bead Cellulose," Die Angewandte Makromolekulare Chemie, 53, pp. 73-80 (1976), describes several derivatized celluloses prepared in bead form.